The average radiation strength in this entity is often expressed as a multiple of the Habing field.  In it, Stromgren spheres are formed around sources of ionizing radiation.  The MRN distribution predicts that one type of matter here is distributed as radius to the -3.5.  A peak at 2175 angstroms in its extinction curve has been attributed to the presence of silicates and amorphous carbon, while its emission spectrum features bands in the infrared due to (*) polycyclic aromatic hydrocarbons.  Radiation intensity here plummets for wavelengths below the Lyman edge.  Observations of pulsar dispersion and the 21 centimeter line are used to trace the presence of ionized and neutral gas in it.  At the heliopause, its pressure is balanced by that of the solar wind.  For 
The average radiation strength in this entity is often expressed as a multiple of the Habing field.  In it, Stromgren spheres are formed around sources of ionizing radiation.  The MRN distribution predicts that one type of matter here is distributed as radius to the -3.5.  A peak at 2175 angstroms in its extinction curve has been attributed to the presence of silicates and amorphous carbon, while its emission spectrum features bands in the infrared due to (*) polycyclic aromatic hydrocarbons.  Radiation intensity here plummets for wavelengths below the Lyman edge.  Observations of pulsar dispersion and the 21 centimeter line are used to trace the presence of ionized and neutral gas in it.  At the heliopause, its pressure is balanced by that of the solar wind.  For 10 points, name this mixture of rarefied gas and dust that fills the space between stars.
The average radiation strength in this entity is often expressed as a multiple of the Habing field.  
{interstellar medium}